Sewing machine with multi-needle supporting arm

ABSTRACT

A sewing machine with a multineedle supporting arm is provided with an oscillating thread gripper moving transversely to the direction of the sewing operation for forming below the throat plate a thread loop into which enter the sewing needles with their upper thread. A horizontal thread spreader fixedly attached to and moving with the material feeder extends with one end provided with a holding tongue into the thread loop to hold the latter temporarily during the rearward movement of the thread gripper, so as to provide an additional length of lower thread on one side of the row of needles which supply the upper thread, said additional length of lower thread is necessary for producing a seam.

States Patent Schinzel et al.

SEWING MACHINE WITH MULTI- NEEDLE SUPPORTING ARM Inventors: Fidelius Schinzel, Karlsruhe; Helmut Schwannecke, Ettlingen, Germany Industrie-Werke Karlsruhe Augsburg Aktiengesellschaft, Karlsruhe, Germany Filed: Jan. 15, 1971 Appl. No.: 106,677

Assignee:

Foreign Application Priority Data Jan. 21, 1970 Germany ..G 70 01 852.9

US. Cl ..112/l99 Int. Cl. ..D05b l/06 Field of Search ..1 12/199, 200, 197, 198

References Cited UNITED STATES PATENTS 10/1933 Maier ..ll2/l99 2,975,737 3/1961 Lukins ..1 12/197 726,310 4/1903 Klemn 3,301,206 l/ 1967 Lanzendorfer ..l 12/ 199 Primary ExaminerH. Hampton Hunter Attorney-Singer, Stern & Carlberg [5 7] ABSTRACT A sewing machine with a multineedle supporting arm is provided with an oscillating thread gripper moving transversely to the direction of the sewing operation for forming below the throat plate a thread loop into which enter the sewing needles with their upper thread. A horizontal thread spreader fixedly attached to and moving with the material feeder extends with one end provided with a holding tongue into the thread loop to hold the latter temporarily during the rearward movement of the thread gripper, so as to provide an additional length of lower thread on one side of the row of needles which supply the upper thread, said additional length of lower thread is necessary for producing a seam.

2 Claims, 3 Drawing; Figures PATENTEUHARZYISTS 3 722 43 SHEET 1 BF 3 FIG I IN V EN TORS A Wok/WK;

PATENTEUHARZYIQB SHEET 2 OF 3 FIG 2 IN V EN TORS fideiz'ass biny ia h'ebpui S'rbwa M ed ATTORNEYS PATENTEDHARZ 7 i975 SHEET 3 [IF 3 FIG 3 SlEWlNG MACHINE WITH MULTl-NEEDLE SUPPORTING ARM The invention relates to a sewing machine with a multineedle supporting arm which is provided with a thread gripper oscillating transversely to the direction of the sewing operation for forming a thread loop into which enter the needles, each of which guides an upper thread.

Multineedle sewing machines are employed for producing elastic seam connections in woven goods, knitted goods and the like and are also used, for instance, for sewing elastic bands to elastic materials. Within the range for the seam connections, it is required, particularly in garments, that no appreciable impairment of the own elasticity of the sewing materials takes place. it is an important requirement that for the sake of great elasticity and also for a faultless formation of such a seam connection a sufficient amount or length of lower thread is available which by a gripper moving in the same cycle as the sewing needles will be formed into a thread loop which is disposed below the throat plate and into which for the purpose of forming a seam the needles enter with the upper thread therein.

It is customary when forming large thread loops to employ relatively large gripper movements. In socalled support arm machines which are a special type of the above-mentioned sewing machine, it is not possible to produce such large gripper movements because this would lead to undesirable large dimensions of the supporting arms.

Sewing machines with multineedle supporting arms are employed particularly for the production of elastic seams in tube-shaped garments-such as sleeves or the like. The seam connections produced in such type of machines, however, do not meet the today requirements of the textile industry.

In order to overcome this disadvantage, it has been proposed heretofore to provide multineedle support arm sewing machines with an empty needle in addition to the needles on a needle carrying rod which are used for guiding threads. It is known that in such a multineedle sewing machines the needles are arranged in a single row extending substantially vertically to the feed direction of the sewed material. The needles after penetrating the sewed material enter for the purpose of forming the seam into a thread loop formed by the gripper below the throat plate.

During the return movement of the gripper the thread loop is tensioned by engaging the needle disposed outside of the reversing point of the gripper point, whereby the lower thread length is fixed. According to this known feature, the needle about which the thread loop has been placed and is tensioned, does not guide an upper thread so that for the formation of the seam there is available a needle which guides an upper thread at a double distance from this empty needle, so that a correspondingly additional lower thread length is available.

With the described provision of an empty needle to the other needles which guide a thread, it is possible to assure a sufficient length of the lower thread, but this is only possible up to limited sewing speeds. When the needles penetrate the sewing material the resulting friction causes a substantial heating of the needles and when the number of stitches reaches 4,000 per minute or more, then the heating can only be controlled when one continuously dissipates the heat in the needles along the length of the upper threads passing through an eye of the needles. The empty needle, however, which does not guide a thread will become very hot after a relatively short sewing period. This heating is a disadvantage at high sewing speeds, particularly when the needles are used to sew synthetic fabrics, because the temperature produced by the empty needles will be above the melting point of the synthetic material which is being sewed. In addition the employment of empty needles produces an unfavorable picture of the seam since the empty needles produce rows of stitches which remain visible after the seam has been completed.

An object of the invention is a supporting arm sewing machine which operates without any empty needles and avoids the disadvantages of the same, whereby however the elasticity and the appearance of the seams will be in accordance with that required of modern textile products.

The invention, therefore, relates to a sewing machine with a multineedle supporting arm provided with an oscillating gripper moving transversely to the sewing direction for the purpose of forming a thread loop into which needles enter which each guide an upper thread. According to the invention a thread spreader is employed which holds the thread loop in the range of the gripper reversing point at least over a substantial portion of the rearward movement of the gripper.

The thread spreader which seizes the thread loop after formation of the same in the range of the gripper reversing point holds the thread loop until the gripper has been returned such a distance that a tightening of the formed thread loop can no longer take place. This thread spreader obviously is disposed below the throat plate of the sewing machine and is movable between its holding and release position in the same cycle as the gripper movement.

In accordance with an important object of the invention the thread spreader in a simple manner is constructed as a holding tongue which is reciprocable in the sewing direction of the sewing machine in such a manner that the spreader at the moment the gripper returns enters laterally into the thread loop which is being formed, so that the lower thread is tensioned over the holding tongue and thereby in view of the axial movement given the gripper, which is superimposed to the rearward movement of the same, is approximately triangularly tensioned. As soon as the gripper has performed its rearward movement over such a distance that a tensioning of the lower thread no longer is to be i feared, the holding tongue is withdrawn from the thread loop and the continued sewing operation takes place by employing the lower thread which now is available in sufficient length.

Another object of the invention is to construct the thread spreader as a wire hoop which is disposed substantially in the horizontal plane of the thread loops and has a U-shaped section which approximately faces away from the reversing point of the gripper point and whose free end of one leg is provided at its rear end at the mentioned reversing point with a lateral offset which serves as a holding tongue.

Still another object of the invention resides in this that the thread spreader is fixedly connected with the feeder which advances the sewing material so that no special drive mechanism is required for this thread spreader.

The described arrangement of the thread spreader of the invention has the result that a supporting arm sewing machine is produced in which in a very simple manner and without a special enlargement of the size of the supporting arm a sufficient length of the bottom thread is assured without employing any empty needles as it was heretofore considered necessary in sewing machines of this type, whereby at the same time a satisfactory sewing of the sewing material is assured.

The invention will now be described with reference to the accompanying drawings which illustrate by way of example a specific embodiment of the invention. However, the invention is not limited to this particular embodiment.

Referring to the drawings:

FIG. 1 illustrates in a perspective view a supporting arm of a sewing machine together with seam-forming parts, but without the throat plate, in which the thread gripper for forming the thread loop is illustrated in a fully outwardly pivoted position.

FIG. 2 illustrates a view similar to FIG. 1, but illustrates a position in which the thread spreader is introduced into the thread loop, while the thread gripper performs its rearward movement; and

FIG. 3 illustrates also a perspective view similar to FIG. 1 in which, however, the thread spreader has released the thread loop and the upper threads have been introduced into the thread loop, while the thread gripper is illustrated in its withdrawn position.

Referring to the drawings, in the supporting arm of the not-completely-illustrated sewing machine is mounted rotatably and axially slidably (for so-called 4- motion operation of the looper as illustrated in US. Pat. No. 2,975,737 to Lukins) a horizontally disposed gripper shaft 11 which has fixed thereto a thread gripper 12. The free or upwardly extending end of the thread gripper 12 comprises an upper arc-shaped section 13 which oscillates below the not-illustrated throat plate during the rotation of the gripper shaft 11 between the end positions shown in the FIGS. 1 and 3, respectively, and in a direction substantially at right angles or vertical to the horizontal direction of the seam, which direction is indicated by an arrow 14. Between these end positions the upper section 13 of the thread gripper 12 moves to and fro. The lower thread 15 is guided toward the gripper 12 by a thread guide 16 and after passing through a not-illustrated additional guide passes through a guide aperture 17 in the outer end of the gripper section 13. From this gripper section 13 the thread is guided substantially upwardly for the purpose of forming the substantially horizontally disposed thread loop 18. The movement of the sewing material is accomplished in known manner by a feeder 19 in the direction of the arrow 14.

The thread spreader 20 is constructed as a wire hoop and is provided with a U-shaped section 21 arranged substantially in the same horizontal plane in which the thread loop 18 is formed. The curved portion of the U- shaped section extends approximately in the advancing direction of the gripper section 13 and toward the side remote from the seamforming members proper. The free ends of the two spaced legs of the U-shaped section 21 are approximately bent at a right angle in the sewing direction and in opposite directions. One of these bent free ends of the legs extends approximately into the range of the reversing point of the thread guiding aperture 17 in the thread guide section 13 toward the direction of the thread loop 18 formed by the thread gripper 12 and constitutes a holding tongue 22 having a very short length in axial direction of the thread spreader 20. The rectangularly bent free end of the other leg forms a long fastening rod 23 which extends in the longitudinal direction of the support 24 (FIG. 2) and parallel to the sewing direction of the feeder'19. This fastening rod 23 extends adjacent the stitch-forming members through a bracket 25 which is fixedly attached to the feeder 19 and in spaced rearwardly relation to this bracket 25 the rod 23 is attached by a holding screw 26 to the support 24 in such a manner that an axial adjustment of the rod 23 and therewith of the thread spreader 20 in relation to the support 24, can be accomplished within specific limits.

In FIG. 1 the needles 27, which are attached to an upwardly and downwardly movable vertical needle bar, are out of engagement with the sewing material; and the thread gripper 12 for the purpose of forming a loop has been pivoted into one of its end positions. In this position of the stitch-forming members the thread spreader 20, which is fixedly attached to the feeder 19, will be moved in axial direction in such a manner that its holding tongue 22 engages the returning thread portion of the thread loop 18 above the thread gripper section 13.

In FIG. 2 the sewing needles 27 during the continued sewing operation enter into the sewing material, and the thread gripper 12 moves from the position shown in FIG. 1 toward its end position shown in FIG. 3. When this takes place the thread loop 18 formed by the thread gripper 12 is firstly held by the holding tongue 22 while the thread spreader 20 initially remains unchanged in its position. FIG. 2 illustrates particularly that the thread gripper 12 during the start of its rearward movement performs a slidable movement in axial direction with respect to the support 24 of the feeder 19 in the manner disclosed in the above mentioned patent so that a triangular thread loop 18 is formed into which enter the sewing needles 27 during the continuous sewing operation as illustrated in FIG. 3. Each of these sewing needles 27 carry an upper thread.

After the thread gripper 12 has performed a substantial portion of its rearward movement and the sewing needles 27 have completely entered the thread loop 18 the feeder 19 and the thread spreader 20 fixedly attached thereto move together with the feeder 19 rearwardly from the sewing area, whereby the holding tongue 22 of the thread spreader 20 is withdrawn from the thread loop 18 so that the thread loop 18 is released. The seam proper is then produced in customary manner, but compared with conventional sewing machines there has been made available as additional lower thread material the thread loop section 18.

What we claim is:

1. In a multi-needle sewing machine,

a. a stationary supporting frame,

b. a sewing material feeder mounted in said frame for reciprocal movement in a predetermined horizontal direction,

be withdrawn from said loop when the looper has completed a substantial portion of its return movement away from said one end position.

2. The sewing machine according to claim 1, in

5 which said thread spreader comprises a wire member having a substantially U-shaped section disposed in the plane of the thread loop to be formed and having one leg of said U-shaped section bent to form said holding tongue, while the other leg is bent to form a rod section 10 which is longitudinally adjustably secured to said feeder. 

1. In a multi-needle sewing machine, a. a stationary supporting frame, b. a sewing material feeder mounted in said frame for reciprocal movement in a predetermined horizontal direction, c. a thread looper mounted in said frame for reciprocal movement transversely of said predetermined direction between two end positions to form a thread loop through which the needles, each carrying a thread, are adapted to enter and be withdrawn in coordinated sequential relation with the movements of said feeder and looper, and d. a loop spreader secured to said feeder for movement therewith in said predetermined substantially horizontal direction and including a holding tongue adapted to enter said loop when the looper is in the vicinity of one of said end positions, and to be withdrawn from said loop when the looper has completed a substantial portion of its return movement away from said one end position.
 2. The sewing machine according to claim 1, in which said thread spreader comprises a wire member having a substantially U-shaped section disposed in the plane of the thread loop to be formed and having one leg of said U-shaped section bent to form said holding tongue, while the other leg is bent to form a rod section which is longitudinally adjustably secured to said feeder. 